Process for the production of hydrocarbon biofuels

ABSTRACT

A method of deoxygenating a feedstock, comprising at least one oxygenated organic compound, to form a hydrocarbon product, comprising the steps of: contacting the feedstock with a catalyst under conditions to promote deoxygenation of the at least one oxygenated compound, wherein the catalyst comprises a mixed metal oxide of the empirical formula: (M 2 ) y (M 1 )O—ZnO—(Al 2 O 3 ) x  is disclosed. The invention is useful in the production of renewable fuels, such as renewable diesel, and jet fuel.

FIELD OF THE INVENTION

The present disclosure relates to methods, compositions, and uses of decarbonylation and decarboxylation catalysts to produce renewable hydrocarbons.

BACKGROUND OF THE INVENTION

Biofuels are fuels produced from biomass—organic matter derived from living, or recently living organisms. Biofuels, as opposed to fossils fuels, are renewable resources and can provide a sustainable supply of fuel. However, compared to fossil fuels, biomass is more functionalized and requires defunctionalization in order to make it readily usable with existing fuel consumption technologies¹.

Biodiesel, a first generation biofuel, is produced using a transesterification process resulting in a fuel that is chemically different from petrodiesel, because it contains oxygen atoms in the form of a fatty acid methyl ester. This results in a type of diesel fuel, which, though environmentally more friendly than petrodiesel fuel, corrodes a standard internal combustion diesel engine. The presence of oxygen in biodiesel reduces energy density. Biodiesel also has issues of reduced fluidity at low temperature and difficulties in long term storage due to oxidative degradation of its unsaturated components. Thus, biodiesel is not typically used as a complete replacement for petrodiesel fuel, but is rather blended with petrodiesel. Biodiesel is a first generation biofuel, meaning that only a portion of the energy potentially available in the biomass is used.

In contrast, renewable diesel, also called green diesel, second generation diesel, and drop-in diesel, is a second generation biofuel that overcomes the drawbacks of biodiesel. This is because renewable diesel is functionally similar and as oxygen-free as petrodiesel. Renewable diesel can be simply “dropped-in” in place of petrodiesel.

To produce renewable diesel, oxygen needs to be removed from biological fats and oils found in the biomass starting materials. Deoxygenating these fats and lipids (e.g. vegetable oils, animal fats, waste cooking oils, and microalgae lipids) produces straight chain alkanes, typically ranging from C₆ to C₂₄.

The hydrodeoxygenation reaction is the most commonly used pathway for deoxygenating oils and fats (e.g. triglycerides) and their derivatives such as fatty acids and fatty acid esters to hydrocarbons. Hydrodeoxygenation of a fatty acid is shown below:

R-COOH+3 H₂→RCH₃+2 H₂O

This pathway requires an external supply of hydrogen and is energy-intensive, requiring high pressure and an expensive hydrogen feed. A commonly used process using the hydrodeoxygenation pathway is called hydroprocessing/hydrotreating or HEFA (hydroprocessing esters and fatty acids). The resulting fuel is known, for instance, as HEFA fuel, hydrogenated vegetable oil (HVO), or hydrogenation-derived renewable diesel (HDRD).

More recently, a decarboxylation/decarbonylation pathway has been investigated. Under this process, oxygen is removed as a CO₂ or CO group, from the fatty acid (shown below), or the corresponding reaction in respect of the fatty acid ester is carried out. The resultant hydrocarbon product has one carbon less than the parent acid:

R-COOH→RH+CO₂ (decarboxylation)

R-COOH+H₂→RH+CO+H₂O (decarbonylation)

Typically, noble metal based catalysts, especially palladium and platinum, have been used in decarboxylation/decarbonylation reactions^(2,3,4). These noble metal based catalysts generally result in excellent yields of hydrocarbons from free fatty acids. However, palladium and platinum are expensive and can rapidly deactivate. Therefore finding an inexpensive or less expensive catalyst showing similar performance and greater durability is of great interest for use in an industrial setting.

Research on Ni-based catalysts has been carried out. Results have been reported by Crocker and co-workers^(5,6,7,8), as well as the Fu laboratory⁹. The formation of a high amount of coke deposits limits the utility of these catalysts for decarboxylation and decarbonylation reactions.

SUMMARY OF THE INVENTION

It is an object of the present disclosure to obviate or mitigate at least one disadvantage of previously attempted treatments.

In one aspect, it is desirable to find more efficient and scalable processes to produce renewable hydrocarbon fuels from a biomass or components derived from a biomass.

The present invention relates to catalysts for use in deoxygenation reactions, wherein the catalyst is a mixed metal oxide.

In a first aspect, the present invention provides a method of deoxygenating a feedstock, said feedstock comprising at least one oxygenated organic compound, to form a hydrocarbon product, comprising the steps of contacting the feedstock with a mixed metal oxide catalyst under conditions to promote deoxygenation of the at least one oxygenated compound.

In one aspect, the catalyst comprises a mixed metal oxide of the empirical formula:

(M²)_(y)(M¹)O—ZnO—(Al₂O₃)_(x)

wherein M¹ is a metal selected from the group consisting of Ag, Au, Co, Cr, Cu, Fe, Ir, Mo, Ni, Os, Pd, Pt, Rh, Ru, and W; M² is a metal selected from the group consisting of Ag, Au, Co, Cr, Cu, Fe, Ir, Mo, Ni, Os, Pd, Pt, Rh, Ru, and W, but is not the same as M¹; x is 0 or 1; and y is 0 or 1.

In one aspect, M² is selected from the group consisting of Ag, Au, Co, Ir, Ni, Os, Pd, Pt, Rh, and Ru.

In one aspect, M¹ is selected from the group consisting of Co and Ni.

In one aspect, the catalyst comprises a mixed metal oxide of the formula: MO—ZnO—(Al₂O₃)_(x), wherein M is Co, Ni or CoNi, and x is 0 or 1.

Advantages of the present invention may include low cost of the catalyst since it uses mostly non-noble metals, and long life of the catalyst compared with Pd only catalysts.

Advantages of the present invention, when using, in particular the two-step process (i.e. triglycerides are first converted into free fatty acids (FFA) or fatty acid methyl esters (FAME) and then deoxygenated with the present catalyst into hydrocarbons), may include: deoxygenation of FFA and FAME with the present catalyst can occur at near atmospheric pressure (e.g. 0.5 MPa), hydrogen consumption due to the methanation side reaction is minimal, and hydrogen is principally consumed simply to saturate the olefin bonds.

Further advantages, in particular in starting from FAMEs, are that due to the multifunctional nature of the present catalyst, hydrogen can be produced in-situ from the FAMEs (methanol part of FAME). The in-situ hydrogen can saturate the olefin bonds and thus, the requirement of external hydrogen for the saturation may be avoided by using FAMEs instead of FFAs. The present deoxygenation catalyst possess active sites for deoxygenation and also for in-situ hydrogen formation from FAME feedstock or methanol.

Other aspects and features of the present disclosure will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments in conjunction with the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present disclosure will now be described, by way of example only, with reference to the attached Figures.

FIG. 1 shows a scheme for the production of renewable diesel from triglycerides.

FIG. 2 shows a co-precipitation method of catalyst synthesis.

FIG. 3 shows results of a catalyst screening test.

FIG. 4 shows the composition of FAME obtained from canola, palm and carinata oils. For every value shown on the x-axis, the first bar represents canola FAME, the second bar represents palm FAME, and the third bar represents carinata FAME.

DETAILED DESCRIPTION OF THE INVENTION

In one aspect, the present invention provides a method of deoxygenating a feedstock, comprising at least one oxygenated organic compound, to form a hydrocarbon product, comprising the steps of contacting the feedstock with a catalyst under conditions to promote deoxygenation of the at least one oxygenated compound.

In one aspect, the catalyst comprises a mixed metal oxide of the empirical formula:

(M²)_(y)(M¹)O—ZnO—(Al₂O₃)_(x)

wherein M¹ is a metal selected from the group consisting of Ag, Au, Co, Cr, Cu, Fe, Ir, Mo, Ni, Os, Pd, Pt, Rh, Ru, and W; M² is a metal selected from the group consisting of Ag, Au, Co, Cr, Cu, Fe, Ir, Mo, Ni, Os, Pd, Pt, Rh, Ru, and W, but is not the same as M¹; x is 0 or 1; and y is 0 or 1.

In one aspect, M¹ is selected from the group consisting of Co and Ni. In one aspect, M² is selected from the group consisting of Ag, Au, Co, Ir, Ni, Os, Pd, Pt, Rh, and Ru.

In one aspect, the catalyst comprises a mixed metal oxide of the formula MO—ZnO—(Al₂O₃)_(x), wherein M is Co, Ni, or CoNi , and x is 0 or 1.

Definitions

The following terms will be used throughout the specification and will have the following meanings unless otherwise indicated.

The term “biomass,” as used herein, refers to a renewable resource of biological origin, such as plants or animals, such resources generally being exclusive of fossil fuels.

“Biologically-derived oil or fat” as defined herein, refers to oil or fat that is, at least partially, derived from a biomass such as, but not limited to, crops, vegetables, microalgae, and the like.

“Renewable Fuel” as defined herein, refers to a hydrocarbon-based fuel, derived from biomass, suitable for consumption by vehicles. Such fuels include, but are not limited to, diesel, gasoline, jet fuel and the like. “Renewable diesel” refers to herein as green diesel, second generation diesel, or drop-in diesel.

“Renewable Jet Fuel” refers to herein as biojet fuel, aviation fuel, or drop-in jet fuel.

“Triglyceride,” as defined herein, refers to class of molecules having the following general formula:

where R¹, R², and R³ are molecular chains comprising carbon and hydrogen, and can be the same or different, and wherein one or more of the branches defined by R¹, R², and R³ can have unsaturated regions.

A “fatty acid,” or “free fatty acid” (FFA) as defined herein, is a class of organic acids having the general formula R-COOH, where R is generally a molecular chain comprising carbon and hydrogen, which can have unsaturated regions, i.e. R is a saturated (alkyl) hydrocarbon chain or a mono- or polyunsaturated (alkenyl) hydrocarbon chain.

A “fatty acid methyl ester” (FAME) as defined herein, is a class of organic esters have the general formula R-COOCH₃, where R is generally a molecular chain comprising carbon and hydrogen, which can have unsaturated regions, i.e. R is a saturated (alkyl) hydrocarbon chain or a mono- or polyunsaturated (alkenyl) hydrocarbon chain. They are generally derived from vegetable oils by transesterification of fats with methanol.

An “oxygenated organic compound”, as defined herein, is any oxygen containing organic compound, in particular, a carboxylic acid, a carboxylic ester, a ketone, an aldehyde, or a mixture thereof. In particular, the oxygenated organic compound may be a triglyceride, a free fatty acid, a fatty acid alkyl ester, a fatty aldehyde, or a combination thereof. In a further aspect, the oxygenated organic compound is an FFA or a FAME.

“Deoxygenation” refers to the removal of oxygen from organic molecules, such as fatty add derivatives, alcohols, ketones, aldehydes or ethers.

“Decarboxylation” refers to the removal of the carboxyl oxygen from add and ester molecules as carbon dioxide.

“Decarbonylation” refers to the removal of carbonyl oxygen from organic molecules with carbonyl functional groups.

“Lower alkyl” or “lower aliphatic” refers to an alkyl or aliphatic group, respectively, having 1 to 6 carbon atoms.

Feedstock

The feedstock used in the embodiments described herein originates from renewable sources, such as fats and oils from plants, animals, and/or algae, biocrudes from wood, and compounds derived therefrom. Non-limiting examples of suitable materials are wood-based, plant-based, or vegetable-based fats and oils. Suitable materials also include micro and macro algae sources. Algae oils or lipids can typically be contained in algae in the form of membrane components, storage products, and/or metabolites. Certain algal strains, particularly microalgae such as diatoms and cyanobacteria, can contain proportionally high levels of lipids.

Suitable oils include algae oil, babassu oil, camelina oil, carinata oil (from Brassica carinata), castor oil, coconut oil, colza oil, corn oil, flaxseed (linseed) oil, hempseed oil, jatropha oil, jojoba oil, lard, mustard oil, olive oil, palm oil, palm kernel oil, peanut oil, pennycress oil, pongamia oil, rapeseed (canola) oil, rice bran oil, safflower oil, soybean oil, sunflower oil, tall oil, tallow oil, or any combination thereof. In one aspect, the feedstock is an industrial oilseed crop. Suitable material also includes feedstocks from an industrial or other non-biological source, such as, for example industrial waste oils, recycled lipids, yellow and brown greases, and waxes.

Suitable feedstocks comprise an oxygenated organic compound. Such oxygenated organic compound is preferably a carboxylic acid, a carboxylic ester, an aldehyde, a ketone or a mixture thereof. In particular, the oxygenated organic compound may be a triglyceride, a free fatty acid, a fatty acid alkyl ester (wherein the alkyl groups typically contain one to five carbon atoms), a fatty aldehyde and ketone, or a combination thereof. In certain embodiments, the oxygenated organic compound is a triglyceride, a free fatty acid (FFA), a fatty acid methyl ester (FAME) a fatty acid ethyl ester (FAEE), or a combination thereof. In one aspect, the suitable materials comprise C₆-C₂₄ fatty acids, or derivatives thereof, or triglycerides thereof.

Suitable feedstocks usable in the present invention can include any of those which comprise triglycerides, free fatty acids (FFAs), or fatty acid alkyl esters (e.g. FAM Es and/or FAEEs), or a mixture thereof. The triglycerides, FFAs, and FAMEs typically contain aliphatic hydrocarbon chains in their structure having from 6 to 36 carbons, preferably from 10 to 26 carbons, for example from 12 to 24 carbons. Types of triglycerides can be determined according to their fatty acid constituents. The fatty acid constituents can be readily determined using Gas Chromatography (GC) analysis. This analysis involves extracting the fat or oil, saponifying (hydrolyzing) the fat or oil, preparing an alkyl (e.g., methyl) ester of the saponified fat or oil, and determining the type of (methyl) ester using GC analysis. In one embodiment, a majority (i.e., greater than 50%) of the triglyceride present in the lipid material can be comprised of C₈ to C₂₆ fatty acid constituents, based on total triglyceride present in the lipid material. Further, a triglyceride is a molecule having a structure identical to the reaction product of glycerol and three fatty acids. Thus, although a triglyceride is described herein as being comprised of fatty acids, it should be understood that the fatty acid component does not necessarily contain a carboxylic acid hydrogen. If triglycerides are present, a majority of triglycerides present in the biomass feed can preferably be comprised of C₁₂ to C₂₄ fatty acid constituents, based on total triglyceride content. Other types of feed that are derived from biological raw material components can include fatty acid alkyl esters, such FAME and/or FAEE, as well as fatty aldehydes and ketones.

Typically, the feedstock can include at least 0.1 wt % of feedstock based on a biomass source, or at least 20 wt %, or at least 50 wt %, or at least 70 wt %, or at least 80 wt %, or at least 85 wt %, or at least 90 wt %, or at least 95 wt %, or at least 97 wt %, or at least 98 wt %, or at least 99 wt %, or 100 wt %. Optionally, the feedstock can include at least about 1% by weight of glycerides, lipids, fatty acids, fatty aldehydes, fatty acid esters (such as fatty acid alkyl esters), fatty aldehyde ketones or a combination thereof. The glycerides can include monoglycerides, diglycerides, or triglycerides. For example, the feedstock can include at least about 50 wt %, at least about 70 wt %, at least about 75 wt %, at least about 80 wt %, at least about 85 wt %, at least about 90 wt %, at least about 95 wt %, at least about 97 wt %, or about 100 wt % of glycerides, lipids, fatty acids, fatty aldehydes, fatty acid esters, fatty acid alkyl esters, ketones or a combination thereof.

The glycerides, FFAs, and fatty acid alkyl esters of the typical vegetable oil or animal fat contain aliphatic hydrocarbon chains in their structure which have about 6 to about 24 carbon atoms. The oxygen level in the feedstock for natural oils can range from 0.5 to 20 wt % and more typically from 5 to 15 wt %. The feedstocks may contain trace amounts of impurities such as P, Na, Ca, Mg and K originating from the phospholipids, a naturally occurring group of compounds in the oils. These impurities may adversely affect the performance of the deoxygenation process and may need to be removed to ppm levels prior to this step. Typical pretreatment processes employed for this purpose include, but are not limited to, low temperature batch processes using solid adsorbents such as silica gel¹⁰, ion exchange resins¹¹ and clays, and the use of guard reactors using hydrotreating type catalysts operating at higher temperatures that are well known in the hydrotreating art. The feedstock can also contain small amounts of nitrogen compounds derived from animal proteins or chlorophyll. The nitrogen content typically ranges from 0.5 ppm to 5000 ppm. Additional optional pretreatment steps may be used.

The feedstock can also include biodiesel fuels, which contain oxygenated organic compounds, such as FAMEs and fatty acid ethyl esters (FAEE). The feedstock can also include a wax ester, which is an ester of a fatty acid and a fatty alcohol.

Process for Conversion of Triglycerides to Renewable Diesel Fuel

FIG. 1 shows a scheme for the production of renewable diesel from triglycerides, as well as from derivatives (i.e. FFA and FAME) thereof.

Triglycerides can be converted into free fatty acids (FFA) through a hydrolysis reaction:

Conversion of triglyceride into free fatty acids (FFA) or into fatty acid methyl esters (FAME) through a transesterification reaction:

Conversion of triglyceride into fatty acid methyl esters (FAME)

The FFAs and their derivatives can then be deoxygenated through decarbonylation or decarboxylation reactions to form hydrocarbons, in the presence of a deoxygenation catalyst. Deoxygenation reactions are discussed in detail below.

The present application relates to the conversion of the triglycerides, FFAs and/or derivatives to hydrocarbons. These can be further upgraded (e.g. isomerized) to a drop-in fuel product, such as renewable diesel, renewable gasoline or jet fuel.

The feedstock used in the present invention can be any organic hydrocarbon source containing an oxygenated hydrocarbon. Looking at FIG. 1, the feedstock can contain, for example, triglycerides, and/or it may contain FAMEs and/or FFAs, for example.

Triglycerides can be converted into hydrocarbons by either in a single step process or a two-step process. The single-step process involves the direct deoxygenation of triglycerides into hydrocarbons. At low pressure, triglycerides smoke, and thus deactivate catalysts. To avoid smoking of triglycerides, deoxygenation is generally carried out at a hydrogen pressure of 8 MPa and above. However, at 8 MPa hydrogen pressure, the deoxygenation reaction consumes hydrogen due to a side reaction, namely methanation of CO and CO₂. Thus, though the presently described catalyst can be used in a single step deoxygenation process to produce hydrocarbons, it may, in some embodiments, be advantageous to use a two-step process due to lower hydrogen consumption. In the two-step process, the triglycerides are first converted into FAMEs or FFAs. The FAMEs or FFAs are then deoxygenated with deoxygenation catalyst as described herein to form the alkanes. In both cases, the n-alkanes can then be further upgraded into drop-in fuels by methods known in the art.

Deoxygenation Catalyst

In one aspect, the catalyst comprises a mixed metal oxide of the empirical formula:

(M²)_(y)(M¹)O—ZnO—(Al₂O₃)_(x)

wherein M¹ is a metal selected from the group consisting of Ag, Au, Co, Cr, Cu, Fe, Ir, Mo, Ni, Os, Pd, Pt, Rh, Ru, and W; M² is a metal selected from the group consisting of Ag, Au, Co, Cr, Cu, Fe, Ir, Mo, Ni, Os, Pd, Pt, Rh, Ru, and W, but is not the same as M¹; x is 0 or 1; and y is 0 or 1.

In one aspect, M¹ is selected from the group consisting of Co and Ni. In one aspect, M² is selected from the group consisting of Ag, Au, Co, Ir, Ni, Os, Pd, Pt, Rh, and Ru.

In one aspect, the catalyst comprises a mixed metal oxide of the formula MO—ZnO—(Al₂O₃)_(x), wherein M is Co, Ni or CoNi , and x is 0 or 1.

In a specific embodiment, the catalyst can be or can comprise CoO—ZnO, CoO—ZnO—Al₂O₃, NiO—ZnO—Al₂O₃, NiO—ZnO, CoO—NiO—ZnO or CoO—NiO—ZnO—Al₂O₃.

In one aspect, the weight ratio of MO to ZnO (or M¹M²O to ZnO) is from 0.01 to 4.0, or more particularly from 0.25 to 1.5. Generally, the atomic ratio of M to Zn can be from about 0.01:1.2 to about 1:0.25, or more particularly from 0.25:1 to 0.8:0.5. In one aspect, when x is 1, the amount of Al₂O₃ in the catalyst varies from 0.1% to 60%, or more particularly from 1% to 40%.

In one aspect, the catalyst is used in a reduced form, having the formula (M²)y(M¹)—ZnO—(Al₂O₃)x , wherein M¹ is a reduced metal selected from the group consisting of Ag, Au, Co, Cr, Cu, Fe, Ir, Mo, Ni, Os, Pd, Pt, Rh, Ru, and W; M² is a reduced metal selected from the group consisting of Ag, Au, Co, Cr, Cu, Fe, Ir, Mo, Ni, Os, Pd, Pt, Rh, Ru, and W, but is not the same as M1; x is 0 or 1; and y is 0 or 1. In use, the oxide form of the catalyst is typically reduced prior to deoxygenation reaction using reducing agents known in the art, such as hydrogen.

In one aspect, the reduced from of the catalyst can be or can comprise Co—ZnO, Co—ZnO—Al₂O₃, Ni—ZnO-Al₂O₃, Ni—ZnO, Co—Ni—ZnO or Co—Ni—ZnO—Al₂O₃.

In one aspect, the reduced form of catalyst may contain some intermetallic particles of Zn.¹²

Suitable mixed metal oxide compositions can advantageously exhibit a specific surface area (as measured via the nitrogen Brunauer-Emmett-Teller (BET) method using a Micromeritics ASAP 2010 instrument) of at least about 15 m²/g. Additionally or alternately, the bulk metal oxide catalyst compositions can exhibit, in some embodiments, a specific surface area of not more than about 600 m²/g.

The catalyst is a heterogeneous catalyst and may be used as a bulk unsupported catalyst or as a supported catalyst. In one embodiment the catalyst used in the present invention is a bulk catalyst. As used herein, the term “bulk”, when describing a mixed metal catalyst composition, indicates that the catalyst composition is self-supporting in that it does not require a carrier or support. It is well understood that bulk catalysts may have some minor amount of carrier or support material in their compositions (e.g., about 15 wt % or less, about 10 wt % or less, about 5 wt % or less, or substantially no carrier or support, based on the total weight of the catalyst composition); for instance, bulk catalysts may contain an amount of a binder, e.g., to improve the physical and/or thermal properties of the catalyst. Preferably, the bulk metal catalyst comprises at least 90 wt %, more preferably at least 95 wt %, active metals. The remainder of these bulk metal catalysts may be comprised of a suitable carrier or support, or in some embodiments, may contain additional organic compounds.

The mixed metal oxide catalyst may also be a supported catalyst. Supported catalysts contain the mixed metal oxides on a high surface area material (i.e. support). The support may be, for example, alumina, silica-alumina, zeolites, mesoporous aluminosilicates, activated carbon, clay, hydrotalcite, or a metal oxide. In order to prepare a supported catalyst, methods known in the art, such as wet impregnation, may be used. The bulk catalysts of the present invention may be converted to supported catalysts by dispersing the active mixed metal oxide or metal oxide precursors on the support, such as on an activated carbon support.

In one embodiment, the mixed metal oxide catalyst is supported on an activated carbon support having a BET surface area of between 500 and 1500 m²/g. In another embodiment, the catalyst is deposited on a support selected from silica, alumina, silica-alumina, titania, zirconia, clay, zeolites, mesoporous aluminosilicates and mixtures thereof, and the support has a BET surface area of between 100 and 1000 m²/g.

The supported catalyst may contain least 1%, by weight of the mixed metal oxide, based on the total weight of the catalyst, including any other desirable active components as well as an optional support material. The amount of the mixed metal oxide will vary depending on how the catalyst is dispersed on the support.

The bulk catalyst can be prepared by methods know in the art. For instance, it can be prepared by co-precipitating metals with a carbonate solution followed by calcination to form an oxide form of catalyst, as shown in FIG. 2. Alternatively, MO—ZnO can be prepared by impregnating a metal salt solution onto ZnO. Examples of methods for making suitable CoO—ZnO and NiO—ZnO catalysts are known.^(13,14)

The prepared catalyst is generally in oxide form. In use, it is generally activated by in-situ or ex-situ reduction with hydrogen at 400-550° C., 425-525° C., or about 500° C.

Deoxygenation Step

The feedstock is contacted with the deoxygenation catalyst in a suitable reactor. A single or multiple catalyst beds may be used. In one embodiment, the feed is passed over the catalyst in a fixed bed reactor operating in continuous mode. In another embodiment, the feed contacts the catalyst in a slurry bed reactor in continuous mode. Either an upflow or downflow type reactor can be used. Multiple reactors may be used in parallel. Alternatively, the feedstock can also be contacted with the catalyst in a batch reactor. In one embodiment, a continuous downflow fixed-bed reactor system can be used. In one embodiment, the reactor system consists of the following sections: (a) Reagent introduction system, (b) reaction chamber, (c) reaction chamber heating system, (d) pressure control system, (e) product collection system and (f) gas analysis system. Reagent gas and liquid can be fed into the reactor via calibrated mass flow controllers and a metering pump. The reaction chamber can consist of a tubular fixed-bed reactor enclosed in a furnace. Reactor products can be quenched in a knock-out pot. The reactor system can be connected with two gas chromatographs equipped with thermal conductivity and flame ionization detectors, respectively, for the on-line analysis of both reagent and product gases.

The feed is contacted with the reduced form of catalyst at a temperature of less than 500° C., possibly from 200 to 500° C., possibly from 280 to 400° C.

In one embodiment, the catalyst bed temperature of the reaction step can be at least about 260° C., for example at least about 300° C. Additionally or alternately, the reaction temperature can be, in one embodiment, not greater than about 450° C., for example not greater than about 400° C.

In one embodiment, the hydrogen pressure within the reactor is between 101 kPa and 8000 kPa, for example from about 101 kPa to 6000 kPa.

In some embodiments, feedstocks are diluted in a suitable solvent for deoxygenation. Suitable solvents would include hydrocarbons, such as, for example cyclohexane, dodecane or hexadecane. In one embodiment, the solvent is recycled hydrocarbons produced by deoxygenation of fatty acids, fatty esters and triglycerides. In some embodiments, a mixture of two or more hydrocarbons is used as a solvent, for example petroleum distillates. In one embodiment, the solvent is cyclohexane. Alternatively, decarboxylation is carried out without diluting feedstocks with solvents.

In one embodiment, the LHSV of feedstock is between 0.4-3.0 h⁻¹. LHSV refers to the volumetric liquid feed rate per total volume of catalyst and is expressed in the inverse of hours (h⁻¹).

In one embodiment, the disclosed catalysts are capable of deoxygenating at least 50%, at least 75%, at least 80%, at least 90%, or at least 95% of the fatty acids, fatty alkyl esters and triglycerides feedstocks into hydrocarbons. For example, the disclosed catalysts may deoxygenate 40-80%, 60-95%, or 80-100% of the fatty acids, fatty aldehydes, fatty esters and triglycerides feedstocks into hydrocarbons.

The liquid hydrocarbon product is primarily comprised of saturated hydrocarbons (n-alkanes or paraffins) produced by decarboxylation and or decarbonylation in the presence of hydrogen. In one embodiments the liquid product of deoxygenation comprise greater than 70%, greater than 80%, or greater than 90% n-alkanes.

In one embodiment, the catalyst can be used to deoxygenate the organic oxygenated compound, while producing hydrogen in-situ. This has the benefit that the hydrogen demand in a deoxygenation can be met in-situ. In one aspect, this is carried out by co-feeding a lower aliphatic alcohol with the at least one oxygenated organic compound. In one aspect, the alcohol is methanol or ethanol. In one aspect co-feeding one mole of methanol produces two moles of hydrogen via decomposition. In one aspect, the organic oxygenated compound is a triglyceride, a free fatty acid, a fatty acid alkyl ester, a fatty aldehyde and ketone, or a combination thereof. The catalyst of the invention can thus be active simultaneously for decarbonylation and alcohol decomposition to hydrogen, i.e. catalysts of the invention possesses multiple catalytic functionalities. Thus, as mentioned previously, the present deoxygenation catalyst possess active sites for deoxygenation and also for in-situ hydrogen formation from FAME feedstock or from a lower aliphatic alcohol, such as methanol.

The catalysts work not only for the deoxygenation of free fatty acids derived from triglycerides, but also for the deoxygenation of fatty acid methyl esters (FAMEs) and Fatty acid ethyl esters (FAEEs). FAMEs are the principal component of biodiesel. Use of FAMEs as the feedstock has the advantage that (i) the methanol part of the biodiesel reforms into hydrogen, thus reducing the external hydrogen requirements/hydrogen consumption.

Upgrading of Deoxygenation Product Into Drop-In Fuels

The hydrocarbon products of deoxygenation of triglycerides, free fatty acids and fatty acid alkyl esters contain straight-chain paraffins (n-paraffins or n-alkanes). These products can be isolated and separated by distillation or other methods known to person of ordinary skill in the art into renewable blending components for gasoline, diesel and jet fuel. Alternatively, the straight chain paraffin product of deoxygenation can be upgraded into a drop-in fuel through a catalytic isomerization method known in the art.

Experimental

Triglycerides: Triglycerides are the ester of one molecule of glycerol and three molecules of fatty acids. Carinata, canola and palm oils contain primarily triglycerides (98 wt %). Carinata is a member of the mustard family. Its scientific name is Brassica carinata and it produces a non-food oil. The non-food-grade canola oil was derived from damaged canola seeds. Palm oil is derived from the fruit of the oil palms. The amounts of saturated, monounsaturated (one double bond), and polyunsaturated (two or more double bonds) fatty acids in these oils are given below in the Table. Palm oil contains a greater amount of saturated fatty acids than the other two vegetable oils.

TABLE Type of Fatty Acids in Carinata, Canola and Palm Oils Carinata Canola Palm Oil Oil Oil Type of Fatty Acid (wt %) (wt %) (wt %) Saturated fatty acids 6 6 45 Mono unsaturated fatty acids 60 62 44 Poly unsaturated - Two double 18 20 10 bonds Poly unsaturated - Three double 15 11 1 bonds ≤C18 fatty acids 45 95 99 >C18 fatty acids 55 3 1

Carinata oil contains predominantly C₂₂ fatty acids, whereas C₁₈ fatty acids are dominant in canola oil. Palm oil contains an equal amount of C₁₆ and C₁₈ fatty acids.

Thermal Hydrolysis to FFA-Transformation of vegetable oil into free fatty acids (FFA): Triglycerides are converted to free fatty acids through thermal hydrolysis, using a process known in the art¹⁵. The thermal hydrolysis of triglycerides was carried out using 0.5 to 2 w/w initial water to triglyceride at temperatures between 250 and 350° C., under a pressure of 2-8 MPa in a continuous stirred-tank reactor (CSTR).

In a typical example, a CSTR reactor was charged with 250 g of water and 300 g of canola oil. The reactor was heated to 260° C. Autogenous pressure was 2.5 to 3 MPa. The reactor further pressurized to 5.5 MPa with inert gas and stirred at 500 rpm. After completion of the reaction, the reaction mixture was transferred into a separatory funnel. The mixture separated into two phases: the water and glycerol heavy phase, and the fatty acid light phase. The fatty acid phase was separated from the glycerol and water; purified to remove any remaining free glycerol; and then dried with anhydrous sodium sulfate (NaSO₄). The quality of fatty acid product was analyzed by nuclear magnetic resonance (NMR) spectroscopy. The product contains 95 wt % of C₁₆-C₁₈ fatty acids.

The hydrolysis process for carinata oil was carried out at different conditions by varying the temperature and pressure. Applicant found in the current set of experiments that the optimum temperature and pressure for carinata oil were a temperature of 260° C. and a pressure of 5.5 MPa, respectively, for the maximum yield of fatty acids. The observed drops in the yield of fatty acids at lower temperatures and pressures were due to poor solubility of triglyceride in water. Increasing the temperature and pressure increases the solubility of triglyceride in water and speeds up the hydrolysis reaction. The NMR study revealed that the level of glyceride impurities in the product sample was very low, with a selectivity of free fatty acids of 98 wt %. At the optimized hydrolysis reaction conditions, a triglyceride conversion efficiency of 99% was achieved with canola, carinata and palm oils.

Transesterification to FAME-Transformation of vegetable oil into fatty acid methyl esters (FAME): Triglycerides were converted into FAME by an alkali-catalyzed transesterification process using methanol and potassium hydroxide (KOH) according to a reported method¹⁶. The transesterification process was carried out using a methanol to oil molar ratio of 5:1 and 1.0% (wt %, based on oil weight) KOH at 40° C. in a 2-L Erlenmeyer flask setup equipped with a mechanical stirrer and a heater. After completion of the reaction, the reaction mixture was transferred into a separatory funnel and kept for 2 h to get a clear separation between the ester and crude glycerin layers. The top methyl ester layer was separated from the glycerin; purified to remove any remaining KOH, soap and free glycerol; and then dried with anhydrous sodium sulfate (Na₂SO₄) to remove moisture. Finally, the fatty acid methyl ester was filtered to remove Na₂SO₄.

The triglycerides employed were canola oil, carinata oil, and palm oil (discussed above). Gas chromatography (GC) and proton magnetic resonance (H-NMR) were used to characterize the product sample. The H-NMR study revealed that the level of glycerides in the product sample was very low, implying the completion of the transesterification reaction. The GC analysis showed a conversion efficiency of 99.5% with all three vegetable oils: The composition of FAME obtained from canola, palm and carinata oils are shown in FIG. 4.

Deoxygenation Catalyst Preparation and Characterization: The zinc oxide based binary and ternary metal oxide catalysts were prepared by calcinating basic carbonates that were produced by precipitating nitrate solutions of metals with potassium carbonate solution at 50-60° C. as shown in FIG. 2. The textural properties of catalysts as measured by the BET-N₂ physisorption analysis are given the Table below:

TABLE Textural Properties of Deoxygenation Catalyst BET Pore Pore Surface Area Volume Diameter Catalyst (m²/g) (cm³/g) (Å) NiO—ZnO—Al₂O₃ 362 0.54 60 CoO—ZnO—Al₂O₃ 203 0.27 54 NiO—ZnO 108 0.60 221 CoO—ZnO 85 0.35 163 NiO—Al₂O₃ 160 0.34 72

Among these catalysts, NiO—ZnO catalyst was characterized further by X-ray powder diffraction (XRD) and temperature-programmed reduction (TPR).

The XRD pattern of Ni-Zn mixed oxides catalyst after calcination (as-synthesized catalyst) is not shown. The spectrum evidences the presence of NiO (peaks at 43.3, 47.8, 56.7 and 62.7) and ZnO crystalline phases (peaks at 31.8, 34.5, 36.6 and 68.2). The XRD pattern confirms that the calcined catalyst is a mixture of Ni and Zn oxides. The average crystallite sizes for NiO and ZnO were determined using the following Scherrer equation:

d=0.94λ/βcosθ

where 0.89 is Scherrer's constant, λ is the wavelength of X-rays, θ is the Bragg diffraction angle, and β is the full width at half-maximum (FWHM) of the primary diffraction peak (43.3 for NiO and 36.6 for ZnO). The result showed that the catalyst contains nanocrystallites of NiO and ZnO with the average crystallite sizes of 13 and 10 nm respectively.

The catalyst was prepared in oxide form. It was activated by in-situ reduction with hydrogen at 500 ° C. In order to understand the composition of the reduced form of catalyst, the reductive behavior of the calcined catalyst was studied by the temperature programmed reduction (TPR) study. The hydrogen consumption during reduction of the NiO—ZnO catalyst as a function of time was measured to provide a TPR profile. The TPR profile displayed one major peak at 385° C. This peak corresponds to NiO reduction to metallic Ni (Ni¹¹to Ni⁰). The experimental weight loss achieved during reduction up to 500° C., was compared with the theoretical loss. It showed that nickel oxide is the only component of the catalyst that is reduced at the activation temperature up to 500° C. The TPR profile along with the amount of weight loss confirm that the active form of catalyst contains nickel as metallic nickel and Zn as ZnO. The result was in good agreement with conclusions of the reported studies^(17,18).

Conversion of Triglycerides/Fatty Acids/Fatty Esters into Paraffinic Hydrocarbons: Triglycerides/Fatty acids/fatty esters were converted into paraffinic hydrocarbons (n-alkanes) in the presence of a decarboxylation catalyst in a continuous downflow fixed-bed reactor system (see FIG. 3). The required reactor pressure was maintained with hydrogen and inert gas. The mass flow controller was used to maintain the required gas/feed ratio. The feed was pumped into the reactor at the required liquid hourly space velocity (LHSV) using a metering pump. At the end of the time period, a gas sample from the reactor was analyzed by an online gas chromatograph (GC) setup equipped with a flame ionization detector (FID) and thermal conductivity detector (TCD). Reactor liquid products were quenched in a knock-out pot. The liquid product samples were analyzed by GC-FID and NMR.

(i)(a) Decarboxylation/Decarbonylation of FFAs into n-paraffins: The catalytic decarboxylation of free fatty acids from carinata oil was performed with the following mixed metal oxide bulk catalysts (Table below) at a temperature of 330° C. and a hydrogen pressure of 0.5 MPa. The FFA feedstock was diluted with cyclohexane at 1:1 (w/w) and pumped at a LHSV of 1 h⁻¹ with the volume ratio of H₂ to feed at 500.

TABLE Deoxygenation catalyst Catalyst Catalyst Code NiO—ZnO—Al₂O₃ Catalyst C CoO—ZnO—Al₂O₃ Catalyst D NiO—ZnO Catalyst E CoO—ZnO Catalyst F NiO—Al₂O₃ Catalyst I

Product identification and quantification were carried out using NMR spectroscopy and gas chromatography. The result of the catalyst screening test after 48 h of time-on-stream (TOS) is shown in FIG. 3. Catalyst I exhibited moderate activity for the decarboxylation/decarbonylation reaction. The catalysts D and F displayed nearly complete fatty acid conversion, but a slight drop in their selectivity to hydrocarbon product due to their observed byproduct formation. Catalysts C and E were chosen for further study.

The NMR study confirmed the absence of unconverted fatty acids and by-products such as wax esters (esters of fatty acids and a fatty alcohols) and fatty alcohols in these product samples. The hydrocarbon profiles of these samples was determined. The primary products were n-heptadecane and n-heneicosane. Compared with catalyst E, catalyst C displayed significantly more cracking of higher carbon number products into lower carbon number products.

The gas stream at the outlet of the reactor was analyzed, and CO₂, CO and CH₄ were found to be the main compounds. Carbon oxides (CO_(x)) were formed by decarboxylation and decarbonylation reactions. Hydrogenation of CO_(x), and cracking of long-chain hydrocarbons resulted in CH₄. Both routes of CH₄ formation consumed H₂. Catalyst E showed much lower methanation and cracking activities than catalyst C.

The catalytic decarboxylation of free fatty acids from non-food-grade canola oil was studied with catalyst E at the same reaction conditions as for the carinata free fatty acid decarboxylation; and it produced similar conversion and gaseous and liquid product yield results (99 wt % conversion with 98 wt % n-paraffins yield). Heptadecane was the primary product in the product sample.

The decarboxylation activity of catalyst E was investigated in the presence of an inert atmosphere by switching from a hydrogen/argon mixture to pure argon (Ar) during one of the experiments with the carinata free fatty acid feedstock. Four hours after switching, the gas stream contained only carbon oxides. There was no methane formation, which was prevalent in the presence of hydrogen gas. The concentration of carbon oxides in the gas phase started to diminish gradually after the switch to Ar gas. The conversion of fatty acids dropped to 40% within 8 h of time on stream. The liquid phase sample contained mostly unsaturated hydrocarbon compounds.

The amount of liquid and gaseous products formed from carinata FFA over catalyst E is provided in the following reaction stoichiometry, where m denotes the average number of double bonds in the FFA sample. The carinata oil contains an average of 1.5 double bonds per mole (m=1.5):

C_(n)H_(2n+1−2m)COOH+3.3 H₂→C_(n)H_(2n+2)+CH₄+1H₂O+0.2 CO+0.4 CO₂.

At the reaction conditions studied in this work, it was found that around 40% CO was involved in the water-gas shift reaction and subsequently produced 0.4 moles of hydrogen. Methanation was the side reaction, which consumed around 1.2 moles of hydrogen to hydrogenate around 40% CO into CH₄. The overall consumption of hydrogen was roughly 3.3 moles per mole of fatty acid (for hydrogenation, carbonylation and methanation reactions), which is much less than that of the hydrodeoxygenation (hydrotreating) process of commercial practice, which theoretically requires 4.5 and 16 moles of hydrogen per mole of fatty acid and triglycerides, respectively, for the production of paraffinic hydrocarbon.

The production of in-situ hydrogen to meet the required hydrogen demand for FFA deoxygenation was investigated by co-feeding one mole of methanol with free fatty acids. Catalyst E was active simultaneously for decarbonylation and methanol decomposition to hydrogen. The co-feeding of methanol produced two moles of in-situ hydrogen and consequently reduced the external hydrogen requirement by 70%. The need for external hydrogen can be lowered further by increasing the amount of methanol in the feed. This study indicated that catalyst E possesses multiple catalytic functionalities. So far, a decarboxylation catalyst with these features has not been reported.

(i)(b) Comparative Example-Decarboxylation of FFAs over commercial Pd/C Catalyst: Pd/C catalyst was identified as a best catalyst for decarboxylation/decarbonylation reaction in the literature. The performance of catalyst E was compared with that of a commercial Pd/activated carbon catalyst (Sigma Aldrich) at a temperature of 330° C., at a hydrogen pressure of 2 MPa, and an LHSV of 1 h⁻¹. Unlike catalyst E, the Pd/C catalyst failed to achieve complete conversion of carinata free fatty acids. It showed 25% less conversion than catalyst E during the first 24 h. The Pd/C catalyst deactivated rapidly; as a result, its conversion decreased by 70% compared with that of catalyst E at the end of 72 h.

Both catalysts showed a similar selectivity profile to C₁₅-C₂₁ paraffins, but different selectivity towards gaseous products (CO₂ and CO). Reactants and products were quantified to derive the reaction stoichiometry (see below equation). The Pd/C catalyst consumed 2.8 moles of hydrogen and produced around one mole of CO and one mole of H₂O per each mole of free fatty acids reacted.

C_(n)H_(2n+1-2m) COOH+2.8 H₂→C_(n)H_(2n+2)+0.9 H₂O+0.9 CO+0.1 CO₂

The composition analysis showed that the carinata FFA sample contained an average of one and a half double bonds per mole (m=1.5). The quantification of products in the decarboxylated sample evidenced that the conversion process involved, first, saturation of olefinic bonds (C═C, C≡C) and then deoxygenation via decarboxylation or decarbonylation routes. Hydrogenation (saturation) of olefinic bonds of carinata FFA requires theoretically 1.5 moles of hydrogen. Deoxygenation via decarbonylation requires 1 mole of hydrogen, whereas no hydrogen is needed for decarboxylation. The experimental result as shown in the above stoichiometric equation matches with the decarbonylation route of deoxygenation over Pd/C catalyst. The formation of CO as a primary gaseous product with catalyst E indicated that it follows the decarbonylation route, like Pd/C catalyst.

(ii) Decarboxylation/Decarbonylation of FAMEs into n-paraffins: Decarboxylation of FAME was carried out in a fixed-bed reactor at temperature, pressure, hydrogen gas/oil ratio, and LHSV of 350° C., 0.5 MPa, 500 (v/v), and 1 h⁻¹, respectively. The product sample was collected after 48 h of time-on-stream. Catalyst E achieved complete conversion of, canola and carinata FAME feedstocks into paraffinic hydrocarbons, with 100% theoretical yield. Both FAME and free fatty acid feedstocks yielded products with similar hydrocarbon profiles. The NMR and GC studies of product samples of canola and carinata FAMEs confirmed this.

The outlet gas stream of canola FAME decarboxylation contained CO as a primary product (see below equation).This indicated that FAME follows the same decarbonylation route as FFA. The canola FAME used in this study has an average of 1.2 double bonds (m=1.2).The quantification of the amount of hydrogen in the inlet and outlet streams showed that catalyst E produced around two moles of in-situ hydrogen from FAME as a by-product. Because of this in-situ hydrogen, only 0.2 moles of external hydrogen per mole of FAME was required for the conversion of canola FAME into paraffinic hydrocarbon product.

C_(n)H_(2n+1-2m) COOCH₃+0.2 H₂→C_(n)H_(2n+2)+0.1 CH₄+0.05 H₂O+1.9 CO+0.1 CO₂

Catalyst E required only 0.2 moles of H₂ for the conversion of canola FAME into paraffinic hydrocarbons. Methanol co-feeding with FAME was studied as a way to completely eliminate the need for external hydrogen supply. A decarboxylation experiment was conducted by co-feeding of one mole of methanol with canola FAME. The co-fed methanol produced two moles of H₂; as a result, the outlet gas stream contained 1.5 more moles H₂ than the inlet gas stream. This study indicated that the amount of hydrogen required to convert FAME into paraffinic hydrocarbons can be met by the by-product hydrogen (formed from FAME) and in-situ hydrogen from methanol.

Palm oil triglycerides contain predominately C16 and C18 fatty acids. Decarboxylation/decarbonylation of palm FAME with Catalyst E was carried at the same reaction conditions as for the canola FAME for 15 days of on time-on-stream (TOS). The performance of catalyst was evaluated at various TOS in terms of conversion and n-paraffins yield. Catalyst E achieved complete conversion of the palm FAME feedstock into n-paraffinic hydrocarbons, with 100% theoretical yield during the entire run period. Chromatograms of liquid samples were collected at different run times. Pentadecane and heptadecane are the major products of palm oil decarboxylation. The hydrocarbon composition of liquid samples collected at the different run periods was determined and is shown in the following table.

Concentration (wt %) Hydrocarbon Day 1 Day 2 Day 7 to 10 Day 12 to 15 Tridecane 1 1 1 1 Pentadecane 44 46 45 45 Hexadecane 3 3 1 3 Heptadecane 45 46 48 46 Octadecane 3 3 3 3 Nonadecane 1 1 1 1 Eicosane 2 0 0 0

Upgrading of n-Paraffins into Drop-in Fuel: The product (n-paraffins) of decarboxylation can be upgraded into drop-in fuel through a catalytic hydroisomerization process, which is well known in the art.

The above-described embodiments are intended to be examples only. Alterations, modifications and variations can be effected to the particular embodiments by those of skill in the art. The scope of the claims should not be limited by the particular embodiments set forth herein, but should be construed in a manner consistent with the specification as a whole.

References

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1. A method of deoxygenating a feedstock, comprising at least one oxygenated organic compound, to form a hydrocarbon product, comprising the steps of: contacting a catalyst with a reducing agent to form a reduced catalyst, contacting the feedstock with the reduced catalyst under conditions to promote deoxygenation of the at least one oxygenated organic compound, wherein the catalyst is a mixed metal oxide consisting essentially of: ZnO; a metal oxide M¹, where the metal of the metal oxide M¹ is selected from the group consisting of Ag, Au, Co, Cr, Fe, Ir, Ni, Os, Pd, Pt, Rh, Ru, and W; optionally a metal oxide M², where the metal of the metal oxide M² is selected from the group consisting of Ag, Au, Co, Cr, Cu, Fe, Ir, Ni, Os, Pd, Pt, Rh, Ru, and W, but is not the same metal as the metal of the metal oxide M¹; and optionally aluminum oxide.
 2. method of claim 1, wherein the mixed metal oxide consists essentially of: ZnO; a metal oxide M¹, where the metal of the metal oxide M¹ is selected from the group consisting of Ag, Au, Co, Cr, Fe, Ir, Ni, Os, Pd, Pt, Rh, Ru, and W; a metal oxide M², where the metal of the metal oxide M² is selected from the group consisting of Ag, Au, Co, Cr, Cu, Fe, Ir, Ni, Os, Pd, Pt, Rh, Ru, and W, but is not the same metal as the metal of the metal oxide M¹; and aluminum oxide.
 3. The method of claim 1, wherein the mixed metal oxide consists essentially of: ZnO; a metal oxide M¹, where the metal of the metal oxide M¹ is selected from the group consisting of Ag, Au, Co, Cr, Fe, Ir, Ni, Os, Pd, Pt, Rh, Ru, and W; and a metal oxide M² , where the metal of the metal oxide M² is selected from the group consisting of Ag, Au, Co, Cr, Cu, Fe, Ir, Ni, Os, Pd, Pt, Rh, Ru, and W, but is not the same metal as the metal of the metal oxide M¹.
 4. The method of claim 1, wherein the mixed metal oxide consists essentially of: ZnO; and a metal oxide M¹, where the metal of the metal oxide M¹ is selected from the group consisting of Ag, Au, Co, Cr, Fe, Ir, Ni, Os, Pd, Pt, Rh, Ru, and W.
 5. The method of claim 1, wherein the mixed metal oxide consists essentially of comprises: ZnO; a metal oxide M¹, where the metal of the metal oxide M¹ is selected from the group consisting of Ag, Au, Co, Cr, Fe, Ir, Ni, Os, Pd, Pt, Rh, Ru, and W; and aluminum oxide.
 6. The method of claim 1, wherein M² is present and the metal of the metal oxide M² is Ni or Co.
 7. The method of claim 1, wherein the metal of the metal oxide M¹ is Co or Ni.
 8. The method according to claim 1, wherein the metal of the metal oxide M¹ is selected from the group consisting of Co and Ni, and the metal of the metal oxide M² is selected from the group consisting of Ag, Au, Co, Ir, Ni, Os, Pd, Pt, Rh, and Ru.
 9. The method of claim 1, wherein the catalyst is a bulk catalyst.
 10. The method of claim 1, wherein the catalyst is a supported catalyst, and wherein the support is alumina, silica-alumina, a zeolite, aluminosilicate, a hydrotalcite, a clay, activated carbon, carbon fibre, carbon nanotube, or a metal oxide.
 11. The method of claim 10, wherein the support is activated carbon.
 12. The method of claim 1, wherein the oxygenated organic compound is a carboxylic acid, a carboxylic ester, an aldehyde, a ketone, or a mixture thereof.
 13. The method of claim 12, wherein the oxygenated organic compound is a triglyceride, a free fatty acid, a fatty acid alkyl ester, a fatty aldehyde, or a mixture thereof.
 14. The method of claim 13, wherein the oxygenated organic compound is a fatty acid methyl ester.
 15. The method of any one of claim 1, wherein a lower aliphatic alcohol is co-fed with the oxygenated organic compound to produce hydrogen in situ.
 16. The method of claim 15, wherein the lower aliphatic alcohol is methanol or ethanol.
 17. The method of claim 1, wherein the mixed metal oxide consists essentially of: ZnO; a metal oxide M¹, where the metal of the metal oxide M¹ is Co or Ni; a metal oxide M², where the metal of the metal oxide M² is Co or Ni, but is not the same metal as the metal of the metal oxide M¹; and aluminum oxide.
 18. The method of claim 1, wherein the mixed metal oxide consists essentially of: ZnO; a metal oxide M¹, where the metal of the metal oxide M¹ is Co or Ni; and a metal oxide M², where the metal of the metal oxide M² is Co or Ni, but is not the same metal as the metal of the metal oxide M¹.
 19. The method of claim 1, wherein the mixed metal oxide consists essentially of: ZnO; a metal oxide M¹, where the metal of the metal oxide M¹ is Co or Ni; and aluminum oxide.
 20. The method of claim 1, wherein the mixed metal oxide consists essentially of: ZnO; and a metal oxide M¹, where the metal of the metal oxide M¹ is Co or Ni. 